1. Field of the Invention
The present invention relates to golf balls, and especially, to the structure of a ball composed of several parts.
2. Description of Background and Other Information
Prior art can be divided into two main types of golf balls. On the one hand, there are the so-called "two-piece" solid balls. Their properties are derived from the combination of a rubber mono-piece spherical core and a hard ionomer resin thermoplastic envelope. The main advantage of these balls is their very high performance during long shots by virtue of their considerable initial speed. However, they feel hard on impact, the main reason for this being their substantial rigidity. Thus, during short shots or approach shots, the initial high speed and small contact surface hinders control of the ball. Also, lack of rotational speed adversely affects the behavior of the ball when it falls.
On the other hand, "three piece" rolled balls are known. These are constituted of a solid or liquid central core, of a rubber thread winding and of a thermoplastic envelope either made of ionomer resin or of balata type rubber of a thickness of 1 to 2 mm. The high deformability of the external layers of the rolled core results in a feeling of softness at impact, due to a smaller rate of compression and consequently a greater contact surface. However, this type of ball adversely affects performance during long shots, as opposed to the "two piece" balls.